FDA Approves Pfizer’s Mylotarg 7 Years After it was Pulled From the Market

The US Food and Drug Administration (FDA) on Friday approved Mylotarg (gemtuzumab ozogamicin) for the treatment of adults with newly diagnosed acute myeloid leukemia whose tumors express the CD33 antigen (CD33-positive AML) and for patients aged two years and older with CD33-positive AML who have experienced a relapse or who have not responded to initial treatment. 

In 2010, Pfizer voluntarily withdrew the treatment, 10 years after it won accelerated approval, when a confirmatory Phase III trial did not show a clinical benefit and the rate of fatalities as a result of treatment-related toxicity was significantly higher in the Mylotarg arm, the company said.

AML is the most common type of acute leukemia in adults and accounts for approximately 80% of all cases of acute leukemia, Pfizer said. About 21,380 people are expected to be diagnosed with AML in the US in 2017 and "there has been little progress in increasing the long-term survival rate in AML patients. Only one in four patients with AML survive longer than five years," the company added.

FDA said in a statement: "Mylotarg was voluntarily withdrawn from the market after subsequent confirmatory trials failed to verify clinical benefit and demonstrated safety concerns, including a high number of early deaths. Today’s approval includes a lower recommended dose, a different schedule in combination with chemotherapy or on its own, and a new patient population."

Richard Pazdur, director of the FDA’s Oncology Center of Excellence and acting director of the Office of Hematology and Oncology Products, said in a statement: "We are approving Mylotarg after a careful review of the new dosing regimen, which has shown that the benefits of this treatment outweigh the risk. Mylotarg’s history underscores the importance of examining alternative dosing, scheduling, and administration of therapies for patients with cancer, especially in those who may be most vulnerable to the side effects of treatment." 

Mylotarg received orphan drug designation and an FDA advisory committee in July voted 6-1 that the benefits of the treatment outweighed the risks.